1. Field of the Invention
The present invention relates to a karaoke apparatus. More particularly, the present invention relates to a karaoke apparatus in which the separation between a microphone signal containing a voice of the singer and a sound effect based on the microphone signal is improved, that is, an apparatus in which the sound image localization of each of the microphone signal and the microphone signal sound effect signal is improved.
2. Description of the Related Art
FIGS. 5 and 6 are diagrams respectively showing signal processing systems for a music signal sound (reproduced accompaniment sound) and a microphone input sound in a conventional karaoke apparatus.
FIG. 5 shows a configuration example of a channel reproduction system. A microphone signal which is output from a microphone 10 is input to a microphone signal input terminal 12, passed through a head amplifier 14, and then level-adjusted by a microphone volume controller (attenuator) 16. The level-adjusted microphone signal is branched into a microphone sound effect generation signal path 18 and a direct sound signal path 20. The microphone signal branched to the microphone sound effect generation signal path 18 is level-adjusted by a microphone sound effect volume controller 22, and then supplied to a microphone sound effect generating circuit 24, so that a microphone sound effect signal (an echo, a reverberation signal, or the like) is generated. A combining circuit 26 additively combines the microphone signal (direct sound signal from the singer) and the microphone sound effect signal.
A music signal which is input to a music signal input terminal 42 is branched into a field sound effect generation signal path 48 and a direct sound signal path 50. The music signal branched to the field sound effect generation signal path 48 is supplied to a digital signal processing (DSP) circuit 54 and a field sound effect signal (such as a reverberation field sound effect signal, or a sound image localization sound effect signal) is generated.
Combining circuits 56 additively combine the direct sound passing through the direct sound signal path 50, and the field sound effect signal generated by via the DSP 54.
All microphone signals output from the combining circuit 26 and all music signals output from the combining circuits 56 are additively combined together with respect to each channel (right channel in (Rch IN) and left channel in (Lch IN)) by combining circuits 28. The synthesized signals are level-adjusted by total volume controllers 30, and then amplified by amplifiers 32 to be acoustically reproduced from loudspeakers 34.
FIG. 6 shows a configuration example of a four-channel reproduction system. A microphone signal which is output from a microphone (not shown) is input to a microphone signal input terminal 12, supplied through a head amplifier (not shown), and then level-adjusted by a microphone volume controller (not shown). The level-adjusted microphone signal is branched into a microphone sound effect generation signal path 18 and a direct sound signal path 20. The microphone signal branched to the microphone sound effect generation signal path 18 is level-adjusted by a microphone sound effect volume controller (not shown), and then supplied to a microphone sound effect generating circuit 24, so that a microphone sound effect signal (an echo, a reverberation signal, or the like) is generated. A music signal that is input to a music signal input terminal 42 is branched into a field sound effect generation signal path 48 and a direct sound signal path 50. The music signal branched to the field sound effect generation signal path 48 is supplied to a DSP circuit 54 and four-channel field sound effect signals (such as a reverberation field sound effect signal, or a sound image localization sound effect signal) are generated.
Combining circuits 56 additively combine the direct sound passing through the direct sound signal path 50, and the front two-channel signals of the field sound effect signal.
Combining circuits 27 additively combine the rear two-channel signals of the field sound effect signal and the microphone sound effect signal. Output signals of the circuits are level-adjusted as required by volume controllers (not shown), and then amplified by amplifiers (not shown) to be acoustically reproduced from rear two-channel loudspeakers (not shown).
Outputs of the combining circuits 56 are used as the front two-channel signals of the sound signal. The outputs are additively combined with the microphone sound effect signal for each of the front channels by combining circuits 28. The synthesized signals are further additively combined with the microphone signal of the direct sound signal path 20, by combining circuits 29. The outputs of the additive combining circuits 29 are level-adjusted by volume controllers (not shown), and then amplified by amplifiers (not shown) to be acoustically reproduced from front two-channel loudspeakers (not shown).
In the signal processing configurations shown in FIGS. 5 and 6, the microphone signal is not independently reproduced. Instead, the microphone signal is additively combined with the microphone sound effect signal and the music signal. From the viewpoint that the production of a microphone sound effect signal enables various kinds of effects to be produced in the microphone signal, such configurations are valuable. However, such configurations or the like have a problem in that separation of the microphone signal is in general so poor that vocals become vague.
The primary cause of the problem has been analyzed and studied. It has been discovered that there is interference between a microphone signal and a microphone sound effect signal.
Usually, a microphone sound effect signal is produced by, for example, delaying an echo, reverberation, or the like with respect to a microphone sound, i.e., an input signal. Such a sound effect signal is basically produced on the basis of a microphone sound which is an input signal, and hence has a waveform which is very similar to that of the original microphone sound. This will be discussed in more detail. The production of a sound effect signal is realized by applying various kinds of filtering processes (BPF, LPF, and HPF), or a delay process on an input signal, or, as required, performing a gain control on the input signal. Eventually, the resulting signal cannot be a signal which is quite unlike the input signal. Therefore, a sound effect signal is often delayed in time with respect to a microphone signal and different from a microphone sound in amplitude, but has a waveform which is similar to that of the microphone sound.
Consequently, a sound effect signal is occasionally produced in which a microphone sound effect signal has a phase difference of 180.degree. C. with respect to the original microphone sound signal. In this case, the microphone sound signal and the microphone sound effect signal are different in amplitude from each other but very similar in waveform, and hence the addition of the two sound signals causes the microphone sound signals to be canceled. This is not preferable from the viewpoints of electric properties and psychoacoustics.
In the related configurations, both the microphone signal and the music signal are subjected to additive combination and then output. Although the possibility is low, there may arise a case where, when the music signal contains a component which cancels the microphone signal, the microphone signal is considerably varied.
In both the signal processing configurations of FIGS. 5 and 6, only one kind of sound is generated as the microphone sound effect. Even when the microphone sound effect signal is reproduced by two or four loudspeakers, there arises another problem in that the sound image localization of the microphone sound effect signal is always positioned at the center of the arrangement of the loudspeakers. This problem is not so serious in the two-speaker reproduction. In the case of the four-speaker reproduction, however, a problem is caused in that the place where the microphone sound effect signal is to be localized (the vicinity of the midpoint of the front loudspeakers) is unnaturally different from where the microphone sound effect signal is actually localized (the midpoint of the four loudspeakers).